Thermally stabilized synthetic polyamides

ABSTRACT

Polyamides are stabilized by the incorporation of a mixture of a sterically hindered phenol, a reducing phosphorus compound and sulphur-containing compound selected from a thiophosphate, a thiodipropionate and a thiocarbamate.

United States Patent [1 1 White [451 Sept. 9, 1975 [5 THERMALLY STABILIZED SYNTHETIC 2,739,123 3/1956 Kennerly et a1. 260/457 7 POLYAMIDES 3,595,936 7/1971 Birenzvige et a1. 260/457 3,772,403 11/1973 Wells 260/4585 [75] Inventor: Trevor Raymond White, Pontypool,

England OTHER PUBLICATIONS [73} Assignee: Imperial Chemical Industries Limited, London England Atmospheric Oxidation and Antioxidants, 1965; by

Gerald Scott,-pp.- 188 to 193, 217, 295 and 296, El- [22] Filed: N0v.-30, 1973 sevier Press. [21] Appl No.: 420,575

Primary Examiner-V. P Hoke Attorney, Agent, or Firm-Cushman, Darby & US. Cl 1 4 260/857 TW; Cushman 260/457 P; 260/457 PH; 260/457 PS; 260/4575 R; 260/4585 S; 260/4595 R; 260/4595 H; 260/459 NP; [57] ABSTRACT 260/78 S; 260/857 PG [5]] Int. Cl. COSG 69/46; COSL 77/00 polyamides are Stabilized b the incorporation of a Field of Search... 260/4575 R, 45.95, 45.85 S, 260/457 PS, 45.9, 78 S, 857 TW, 857 PG References Cited UNITED STATES PATENTS 2,705,227 3/1955 Stamatoff 260/457 mixture of a sterically hindered phenol, a reducing phosphorus compound and sulphur-containing compound selected'from a thiophosphate, a thiodipropionate and a thi'ocgrbamate.

.4 Claims, N0 Drawings THERMALLY STABILIZED SYNTHETIC POLYAMIDES The present invention relates to the stabili/ation of synthetic linear polyamides or copolyamides against impairment of their properties by the action of heat and oxygen and by light.

According to the present invention we provide a synthetic linear polyamide or copolyamide in which there have been incorporated from 0.005 to 0.5)? by weight based on the polyamide of a sterically hindered phenol bearing a secondary or tertiary alkyl or cycloalkyl group in the ortho position, from to L000, preferably from to 250. parts per million by weight based on the polyamide of phosphorus in the form ofa reducing phosphorus compound and from 0.005 to 0.571 by weight based on the polyamide of a reducing sulphurcontaining compound selected from the group consisting of a metal salt, an ammonium salt or an organic ester of thiophosphoric acid. thiodipropionic acid and thiocarbamic acid.

Examples of suitable synthetic linear polyamides (which expression is to be understood as including copolyamides) are listed below:

polyhexamethylene sebacamide polyhexamethylene adipamide polyoctamethylene adipamidc polydecamethylene sebacamide Examples or reducing sulphur-containing compounds which may be added are zinc diisopn)pyldithiophosphate. dilaurylthiodipropionate. distear vlthi( )dipropionate, magnesium di-isopropyldithiophosphate. ammonium di-isoprtipyldithiophosphate and potassium di-isopropyldithiophosphate. g

The present invention is particularly adapted to polyamides containing titania or other pigments; and is applicable to both acid-stabilized and base-stabilized poly amides. t t I Conventional adjuvants may also beadded to the polyamides at any convenient stage in their manufacture. for instance; dyes, pigments, dyestuff-formers, plasticizers, resins and antistatic agents such as ethoxyl- 'ated compounds t The present invention includes shaped articles, such as fibres, filaments, yarns, films, fabrics and other textile materials, of the synthetic linear polyamide containing the stabilizing compounds.

The stabilizing compounds may be incorporated. either separately or in combination, in the polyamide by addition at any suitable stage in its manufacture. Pref erably they are mixed with the polyamide starting materials before the polymerization commences. Alternatively, they may be a'dded to the pre-formed polyamide. for instance by dusting them on to the polyamide chip prior to its melting. The stabilizing compounds may be added at suitable points in a continuous polymerization process, such as that carried out in a pipe or coil.

Polypcmilmcthylcne sbhucllmldc 3O The following examples. in which the parts are parts P"lydodccilmcthylcnc illllpumldc by weight. are intended to illustrate, but not to limit. poly-epsilon-caprolactam h mi poly-omega-aminoundecanoic acid poly-m-xylylene adipamide EXAMPLES 144 polyhexamethylene isophthalamide 6.6 nylon was prepared by the conventional method, Copolyamides derived from the following starting {mm hexilmethylcne dlamlne and udlplc acidwith the materials also b mi d; addition, at the beginning of polymerization, of a slurry l. hexamethylene diammonium adipate and epsilon- Cmmlnlng tltimllflfl Q P lp f iwith e capmlacumL g g 40 nese. phosphate. \lhe titanium dioiflde was added n 2. hexamethylene diammonium adipate and hexa- Such amount t h was l f? m mcthylcne diummonium scbucme the f nal polymer. At the same time, N'HIIOLIS stabilizing hcxamcthylene diummonium adipate and hexw additives were incorporated in various amounts.

methylene diammonium isophthalmm 200 denier, 20-filament yarns were melt spun from 4. hexamethylene diammonium terephthalate and the'polymers producejd cdch case Samples f dodecamethy lene diammonium terephthalate, undrawn yams free of s w d 9 ammc f 5. the salts from hexamethylene diamine. adipic acid 4 group figment (culled AEG and measured m equiv} Suitable sterically hindered phenols include those .1 I 'v and Relative VlSCOblty (Ram the conventional manner, listed in Brltish patent specification No. l,209-,592. ilk-WC" as for whiteness. h whiteness Ofthc y was The reducing phllsphomus compmnds whlchimay be measured in terms of hchromaticity (b) ona Meco added include Orthwphosphmousi mctzbphfisphomu- Colormaster Mark V colorimeter, (obtainable from pymphosphomuis hypwphosphnmus and p y p Manufacturers Engineering & Equipment Corporation, phinic acids. and their organic and inorganic salts and wurringtom p USAJ using the rotating dish asset? their 9 i y I bly. The colorimeter was ire-calibrated. Perfect white- Exllmplcs of Such Organic'sults and esters arc: ness was denoted by a value of 0.333. The yarns were hcxilmethylenc dlllmmonium YP P P than heated in air at 200C forf 30 seconds and the dimethyl hydrogen orthophosphite above mentioned tests again carried out. The results tri-isodecyl orthophosphitc obtained are shown in the following table. diethanolammonium hypophosphite 6O Topanol CA (Registereddrade Mark of Imperial triethylammonium hypophosphite Chemical industries Limitedt is essentially tris-( 2- triphenyl orthophosphitc methyl-4-hydroxy-5-tbutylphe'nyl) butane.

EisiAfM- STABILIZING ADDl'l'lVE Initial analysis Change in analxsis Rv AEG (15G h A AEG A CEG A h l 0.05% Topanol CA 0. l'/( zinc di-isopropyl- 39.2 43.5 72 0.326 I0] 5 0,026

dithiophosphate "F ppmP as sodium hypophosphit that the on nylon also contained 5% by weight of an ethoxylated polycaproamide antistatic agent.

b. from 0.005 to 0.5; by eight based on the pol amide ol'a sterically hindered phenol bearing a secondary of tertiary all\ \l or cycloalkyl group in the ortho position:

. lrom H) to 1.000 parts per million by weight based on the polyamide of phosphorus in the form of a COMPARA11VE EXAMPLES reducing phosphorus compound: and

d. from 0.005 to 0.592 by Weight based on the poly- ThCSQ x mple are m il 11 ample 1 -2 X- amide ol a reducing sulphurcontaining compound eept that the stabilizing additives are outside the scope selected from the group consisting of a metal salt. of the present invention. an ammonium salt or an organic ester of thiophos- EXAM- S'I'ABlLIZlNG ADDlTlVl: Initial analysis Change in analysis PLE AEG B A AEG A b N 0.05% Topanol (A l00 ppm P as sodium hypophosphitc 56.8 0.322 13.7 0.029 O 0.1"": Topanol CA l00 ppm P as sodium hypophosphitc 62.8 0.32] 13.4 0.036 [5 0.0571 Topanol (A 100 ppm P as sodium hypophosphite 0.0571 Zinc diisopropyl dithiophosphatc 56.6 0.32! l l.2 0.0.30 16 0.05'?) Topanol (A l00 ppm P as sodium hypophosphite 1- 01% Zinc diisopropyl dithiophosphate 62 7 0.323 7.3 0.024 17 0.05! Topanol CA l00 ppm P as sodium hypophosphite +0.2? Zinc diisopropyl dithiophosphate 6L0 0.32? 3.6 0.018 18 0.05% Topanol (A 50 ppm P as sodium hypophosphitc +0.I'71 Zinc diisopropyl dithiophosphate 60.4 0.323 9.9 0.025 19 0.05% Topanol CA 100 ppm P as barium hypophosphite 0.1% Zinc diisopropyl dithiophosphate 57.0 0.323 7.5 0.02]

20 0.05% Topanol CA 100 ppm P as sodium hypophosphite 0. l71 Zinc diheiuyl dithiocarbonatc 6L4 0.3]4 13.l 0.027

2l 0.05? Topanol (A l00 ppm P as sodium hypophosphitc (H9? Zinc thiodipropionate 75.8 0.321 2l 5 0.044 22 0.05" Topanol (A l00 ppm P as sodium hypophosphitc 0.1% sodium thiodipropionate 64.7 0.322 16.8 0.043 23 0.05% l'opanol ('A 100 ppm P as barium hypophosphite 0.071 Barium thiodipropionate 57.4 0.321 l7.4 0.04]

EXAM LE 24-37 phorie acid. thiodipropionic acid and thiocarbamic 7 acid.

[hmc example m Examples 2. A polyamide according to claim I containing 25 to cup! that the f ""FW 5 of 250 parts per million by weight based on the poly-amide cthoxylated alkylamme anltistatie agent instead of an of phusphmus in the form of the reducing phosphorus cthoxylated polyeaproamlt e. Compound 40 3. A polyamide according to claim I in which the re- (TOMPARA'IIVF. EXAMPLES P-Q ducing phosphorus compound is selected from the group consisting of ortho-phosphorus. meta- These examples are the same as Examples 24-27 exphosphorous. pyro-phosphorous. hypo-phosphorous cept that the stabilizing additives are outside the scope and phenylphosphinie acids. and their organic and inof the present invention. organic salts and their esters.

EXAM- STABILIZING ADDITIVE Initial Analysis Change in analysis PLE AEG B A AEG A h P 0.05 Topanol (A ppm P as sodium hypophosphite 78.0 0.320 22.6 0.032 O 0.1% Topanol CA l00 ppm P as sodium hypophosphite M2 0.3 l7 l6.7 0.029 24 0.059 Topanol CA 100 ppm P as sodium hypophosphitc 0.l/1 Zinc diisopropyl dithiophosphate 86.6 0.322 18.8 0.020 25 0.05% Topanol CA l00 ppm P as sodium hypophosphitc 0.1% Zinc dihen/yl dithioearhonate 83.) 0.3 l4 17.2 0.018 26 0.05: Topanol (A l00 ppm P as sodium hypophosphitc 0.l'/1 Zinc thiodipropionatc 86.6 0.320 24.7 0.045 27 0.05 Topanol CA l00 ppm P as barium hypophosphite +01% Zine diisopropyl dithiophosphate 66.4 0.321 I().4 0.029

What I claim is: ,o 4. A polyamide according to claim I containing an I. A pol amide composition consisting essentially ola. a synthetic linear polyamide:

eth ixylated antistatic compound.

mwszws. 

1. A POLYAMIDE COMPOSITION CONSISTING ESSENTIALLY OF A. A SYNTHETIC LINEAR POLYAMIDE, B. FROM 0.005 TO 0.5% BY WEIGHBASED ON THE POLYAMIDE OF A STERICALLY HINDERED PHENO. BEARING A SECONDARY OF TERTIARY ALKYL OR CYCLOALKYL GROUP IN THE ORTHO POSITIONS C. FROM 10 TO 1,000 PARTS PER MILLION BY WEIGHT BASED ON THE POLYAMIDE OF PHOSPHORUS IN THE FORMUAL OF A REDUCING PHOSPHORUS COMPOUND, AND D. FROM 0.005 TO 0.5% BY WEIGHT BASED ON THE POLYAMIDE OF A REDUCING SULPHURCNTAINING COMPOUND SELECTED FROM THE GROUP CONSISTING OF A METAL SALT AN AMMONIUM SALT OR AN ORGANIC ESTER OF THIOPHOSPHORIC ACID THIODIPROPIONIC ACID AND THIOCARBAMIC ACID.
 2. A polyamide according to claim 1 containing 25 to 250 parts per million by weight based on the polyamide of phosphorus in the form of the reducing phosphorus compound.
 3. A polyamide aCcording to claim 1 in which the reducing phosphorus compound is selected from the group consisting of ortho-phosphorus, meta-phosphorous, pyro-phosphorous, hypo-phosphorous and phenylphosphinic acids, and their organic and inorganic salts and their esters.
 4. A polyamide according to claim 1 containing an ethoxylated antistatic compound. 